Research on the relation between breaker bar movement and volume fluctuations along the Holland coast

Abstract

This thesis concentrates on the autonomous behaviour of the breaker bars in front of the Holland coast in the period 1965-2006. The breaker bars in front of the Holland coast show a seaward movement, starting small at the waterline, growing during their seaward motion and dying out at deeper water. A typical profile in front of the Holland coast has 3 breaker bars present. This pattern repeats itself with a certain cycle time. Research on seven different locations along the Holland coast has indicated different cycle times in different transect along the Holland coast. In these locations a relation between the yearly volume changes of the sediment volume of the Holland coast and the calculated cycle time of the breaker bars is sought. This is done by comparing the cycle time of the breaker bars to the year to year fluctuations of the volume. This research has shown that the seaward motion of the breaker bars have very little influence on the fluctuations of the volume. This means that other processes that cause sediment movement are more dominant. The difference in calculated cycle times indicates that a single breaker bar can move with different speeds, this causes the bar to create a growing angle with the shore. Analysis of yearly measurement have shown that bars can make a so-called barswitch to solve this.